@open-spaced-repetition/sm-2/dist/index.js

Typescript Package for SM-2 Spaced Repetition

// src/Card.ts
var Card = class _Card {
  constructor(cardId = null, n = 0, EF = 2.5, I = 0, due = null, needsExtraReview = false) {
    if (cardId == null) {
      cardId = Date.now();
    }
    this.cardId = cardId;
    this.n = n;
    this.EF = EF;
    this.I = I;
    if (due == null) {
      due = /* @__PURE__ */ new Date();
    }
    this.due = due;
    this.needsExtraReview = needsExtraReview;
  }
  equals(other) {
    return this.cardId == other.cardId && this.n == other.n && this.EF == other.EF && this.I == other.I && this.due.getTime() == other.due.getTime() && this.needsExtraReview == other.needsExtraReview;
  }
  clone() {
    return new _Card(
      this.cardId,
      this.n,
      this.EF,
      this.I,
      new Date(this.due),
      this.needsExtraReview
    );
  }
  toJSON() {
    return {
      cardId: this.cardId,
      n: this.n,
      EF: this.EF,
      I: this.I,
      due: this.due.toISOString(),
      needsExtraReview: this.needsExtraReview
    };
  }
  static fromJSON(json) {
    return new _Card(
      json.cardId,
      json.n,
      json.EF,
      json.I,
      new Date(json.due),
      json.needsExtraReview
    );
  }
};

// src/ReviewLog.ts
var ReviewLog = class _ReviewLog {
  constructor(cardId, rating, reviewDatetime, reviewDuration = null) {
    this.cardId = cardId;
    this.rating = rating;
    this.reviewDatetime = reviewDatetime;
    this.reviewDuration = reviewDuration;
  }
  equals(other) {
    return this.cardId == other.cardId && this.rating == other.rating && this.reviewDatetime.getTime() == other.reviewDatetime.getTime() && this.reviewDuration == other.reviewDuration;
  }
  clone() {
    return new _ReviewLog(
      this.cardId,
      this.rating,
      new Date(this.reviewDatetime),
      this.reviewDuration
    );
  }
  toJSON() {
    return {
      cardId: this.cardId,
      rating: this.rating,
      reviewDatetime: this.reviewDatetime.toISOString(),
      reviewDuration: this.reviewDuration
    };
  }
  static fromJSON(json) {
    return new _ReviewLog(
      json.cardId,
      json.rating,
      new Date(json.reviewDatetime),
      json.reviewDuration
    );
  }
};

// src/Scheduler.ts
var Scheduler = class {
  static reviewCard(card, rating, reviewDatetime = null, reviewDuration = null) {
    card = card.clone();
    if (reviewDatetime == null) {
      reviewDatetime = /* @__PURE__ */ new Date();
    }
    let cardIsDue = reviewDatetime >= card.due;
    if (!cardIsDue) {
      throw new Error(`Card is not due for review until ${card.due}`);
    }
    if (card.needsExtraReview) {
      if (rating >= 4) {
        card.needsExtraReview = false;
        card.due.setDate(card.due.getDate() + card.I);
      }
    } else {
      if (rating >= 3) {
        card.EF = card.EF + (0.1 - (5 - rating) * (0.08 + (5 - rating) * 0.02));
        card.EF = Math.max(1.3, card.EF);
        if (card.n == 0) {
          card.I = 1;
        } else if (card.n == 1) {
          card.I = 6;
        } else {
          card.I = Math.ceil(card.I * card.EF);
        }
        card.n += 1;
        if (rating >= 4) {
          card.due.setDate(card.due.getDate() + card.I);
        } else {
          card.needsExtraReview = true;
          card.due = reviewDatetime;
        }
      } else {
        card.n = 0;
        card.I = 0;
        card.due = reviewDatetime;
      }
    }
    const reviewLog = new ReviewLog(card.cardId, rating, reviewDatetime, reviewDuration);
    return { card, reviewLog };
  }
};
export {
  Card,
  ReviewLog,
  Scheduler
};
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